pH

Please answer Step C & Step D (the answers for steps a & b are provided) in the following problem:

2. Beginning with 150.0 mL of 0.175 M ammonia, determine the solution s pH after each of the following steps:
a) before any additional material is added to the solution, (Answer to this step is pH =11.25)
b) after 25.0 mL of 0.200 M nitric acid, HNO3, is added, (Answer to this step is pH =9.88)
c) after 25.0 mL of 0.400 M ammonium chloride is added to the solution resulting from step (b), and
d) after an additional 25.0 mL of 0.400 M ammonium chloride is added to the solution (be sure to account for the change in volume at each step).